I have just gotten interested in turbocharging. Thinking I might turbo my 4.8 2011 rcsb, 2wd one of these days. But I have a lot of learning to do first.

One question that keeps coming up for me is about turbo headers. It seems that most of the single kits retain a stock manifold and provide a cast turbo manifold. I am wondering why not tubular headers? Is it because the headers might be subject to burning out, so the heavier castings are preferred?

 

I would say it's because the manifolds just work, a simple as that.

You can push well over 1000whp through the stock manifold on a turbo setup. Also there is far less risk to cracking, wear and problem with a stock exhaust manifold.

 

Makes sense. I guess it just seems counter-intuitive to me because I've always thought of stock ci manifolds as being very restrictive. Of course coming from a naturally aspirated perspective. I guess from a blower perspective, too. In those applications, the headers or manifolds are the only exit path. Now that I'm thinking about it, the only place the exhaust from the engine is going in a turbo setup is to the turbine... the "waste" exhaust leaves through the downpipe, which seems plenty big.

I hadn't really thought about it like that until just now. See, I told you I had lots to learn about turbocharging!

So, with intake under pressure, the engine "pushes" the exhaust out without hurting performance/efficiency? The scavenging effect of headers becomes unimportant? Am I getting the concept right?

 

To your original question...I'm going to say cost is the main reason. I don't know anyone who would choose the cast manifolds if you could get turbo headers for the same price. since the trucks come with manifolds and turbo headers cost >$0, it sort of explains itself.

To your other point, I'll just say turbocharging is very dynamic. Lots of turbo concepts seem counter-intuitive at first glance. The engine having to push exhaust out into a restrictive environment is indeed a hindrance to performance, but carefully selected camshafts are used to prevent the power losses from being too drastic. The importance of scavenging varies by application. For daily drivers looking for a little extra street power, it matters less. But for a racing application where you may be limited in compressor size, scavenging has its place.

 

In a perfect world I don't see why anybody would want anything but turbo headers and twins. If you have the money, time, and skills to make it happen, I say go for it. Otherwise like FFDP said you can make a lot of power on a stock manifold and turbo log fairly easily for less money.

I have a Trick kit and don't have a single bad thing to say about it but secretly I would love a nice twin kit.

 

Manifold help retain heat and keep velocity up. Both help with spool

 

We might have something for you soon.
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Turbo it self is a restrictor. You've stuck a fan blade into the exhaust flow.
Now There's more to it then just flow.
Stick a giant turbo on there.
The exhaust will flow more and make less power. Then a properly more restrictive turbo.
Manifolds are proven over 1000+ horsepower to the ground.
There is flow, pulse engery, heat, fitment and function.
Headers take up a huge amount of room and add nothing at most power levels that I have found. .
I've been told over the years it's 50hp, it's 100hp, it's 200hp etc. but have not seen a back to back test proving these claims yet. If true wonder at what power level it really comes into play.

 

My truck is done until I brake something( knock on wood). I couldn't justify a twin kit on my SBE 4 bolt headed motor. I can't even justify a forged bottom end when every engine builders I've talked to says even at my current power levels I could lift a head if something if is off and I get some detonation. Really I think the Trick T4 kits are perfect for 4 bolt headed motors. Not that you can't get more power out of twins or T6 setups on a 4 bolt heads. I just don't see the point in doing it unless you do a fully forged 6 bolt motor. IMO it's too easy to go 10's on a SBE 4 bolt motor with a T4 Trick/Kb setup to justify anything else unless you are willing to spend a whole other level of money. I already spent way more than I intended going into my turbo kit. When something takes a crap on me who knows. Right now I'm just trying to enjoy a 10 sec 5000+ lb 2wd ecsb pickup that is daily drivable even in 100+ degree Phoenix weather. Maybe other people have different opinions than me but this is my opinion and where I'm at until I'm forced to do something different.

 

For me it was ease of packaging on the junk yard build I am doing on my 2007 rcsb . I got the truck for next to nothing and am trying to build the lowest cash out of pocket track only truck I can. I am building everything myself and only buy what I absolutely have to in the quest for low 10's in a gutted / stripped down truck.

 

A twin turbo kit would make an excellent Christmas present! Sign me up!